Apparatus for arc welding



Nov. 1, 193.8. J, E, TRAWER 2,135,129

APPARATUS FOR ARC WELDING Filed June 16, 1934 sets-Sheet l INVENTOR James E Trainer Q I ATTORNEY Nov. 1, 1938. J, E TRA|NER 2,135,129

APPARATUS FOR ARC WELDING Filed June 16, 1954 8 Sheets-Sheet 2 T k 92 U i INVENTOR 3 A James E. Tr'qiner Po ATTORNEY 1933- J. E. TRAINER APPARATUS FOR ARC WELDING Filed June 16, 1954 8 Sheets-Sheet 3 'Fig 4 72 I1 mllll l liflllllli'lillll W i V JUL-[$1. 92 rllllll-llll II I l JH" Mull lljufi INVENTOR cjames E. Trainer ATTORNEY Nov. 1, 1938. 1 E. R j E 2,135,129

APPARATUS FOR ARC WELDING Filed June 16, 1934 8 Sheets-Sheet 4 INVENTOR ames E fluiner BY ATTORNEY Nbv. 1, 1938. J, E, T AINE 2,135,129

APPARATUS FOR ARC WELDING Filed June-l6, 1954 8 Sheets-Sheet 5 Fl 8 V I Z0 /08 707 /09 f V V I 705 g. twig? -MIMEV Z51 "W al i g fiainel" M M EJZQR W ATTORNEY Nov. 1, 1938. TRAlNER 2,135,129

APPARATUS FOR ARC WELDING Filed June 16, 1934 8 Sheets-Sheet 6 H Fig "Mum- Wa k 96 INVENTOR JamesE Trqiner ATTORNEY Nov. 1, 1938. J. E. TRAINER APPARATUS FOR ARC WELDING Filed June 16, 1934 8 Sheets-Sheet 7 Nov. 1, 1938. J, E NE f 2,135,129

APPARATUS FOR ARC WELDING Filed June 16, 1934 8 Sh ts-Sheet 8 INVENTOR James 5'. Trainer YIIIIIIIIIIIIIIIIIIIIIIIIJ k a v -A TORNEY Patented Nov. 1, 1938 APPARATUS FOR ARC WELDING James E. Trainer, Akron, Ohio, assignor to The Babcock & Wilcox Company, Newark, N. J.,

a corporation of New Jersey Application June 16, 1934, Serial No. 730,852

2Claims.

This invention relates to welding machines and more particularly to that class adapted to utilize the electric arc and in which a bare, coated or covered weldrod may be progressively fed to the v weld.

An object of the invention is to provide a machine of the class mentioned so arranged that a weldrod feeding head is, movable longitudinally of the work seam being welded, and yet is adapted for operation in a stationary position with the 'work seam movable relative thereto, whereby the same machine and weldrod feeding head may be utilized for either longitudinal or circumferential seam welding.

A further feature is the provision of a weldrod feeding head having an adjustment of the weldrod feeding device itself. with relation to the same, in addition to the movement mentioned in the preceding paragraph and which thus renders it possible for the operator to exactly position the end of the weldrod with respect to the width dimensions of the seam.

The weldrod feeding head is also so constructed that the angularity of the rod with respect to the work seam may be adjusted in planes at right angles to each other to provide the proper weldrod inclination for the type of scam being worked upon, whether it be either a longitudinal, transverse or a circumferential seam.

Another important feature of the invention is the feeding of the weldrod with feeding rollers having a resiliently yielding frictional engagement with the weldrod and normally automatically operated for a rate of feed suitable for the type of work and materials used. but having a manual adjustment independent of the automatic feed, and a manual adjustment for varying and setting the rate of automatic feed, as well as an automatically actuated adjustment of the auto- 0 matic feed varying the latter in accordance with conditions at the arc, or more broadly stated in accordance with conditions in the welding zone. Additionally, the invention includes a weldii'ii; current circuit and a Welding current and weld- 43 rod feed control circuits, coordinated and coopcrating for control of the conditions in the weld.- ing zone and providing a system which is especially adapted for the utilization of alternating current at the arc. The form of weldrod prefer- .ao ably used is that disclosed in my copending application for United States Letters Patent, Serial No, 637,234, filed October 11, 1932, since matured into Patent No. 2,057,861, dated, Oct. 26, 1936.

If desirable, the machine, as used for circumferential. and longitudinal welds on tank bodies,

penstocks and the like, may include a backing-up member or a chill which is stationary for circumferential seams, while the work moves through a suitable work drive, but which may be moved longitudinally of'the work seam coincidentally with the weldrod feeding head when the work being operated upon is, itself, stationary.

With the foregoing features stated the invention will now be described in connection with the accompanying drawings illustrating a practical form of the same and wherein:

Fig. l is a side elevation of the machine as adapted to the welding of a circumferential scam in a tank body, penstock unit or the like, with the elements being worked upon shown in section;

Fig. 2 is the electrical diagram for the coordinated and cooperating circuits;

Fig. 3 is an enlarged side elevation of my improved form of weldrod feeding head showing the latter as welding a longitudinal seam;

Fig. 4 is a top plan view of the weldrod feeding head shown in Fig. 3;

Fig. 5 is an end elevation in the direction of the arrows 5-5 of Fig. 3;

Fig. 6 is a side elevation of the weldrod feeding head as shown in Fig. 5 and in the direction of the arrows 6- 6 of Fig. 5 or, in other words, this View is of the opposite side from that shown in Fig. 3; Fig. 7 is a sectional view on the line 1-1 of Fig.

Fig. 8 is an enlarged view, partly in section and in side elevation, of the angular adjustment for the weldrod in one plane, as also shown in Figs. 3 and 6; i

Fig. 9 is a. sectional view, in side elevation, of the gear box shown in Fig. 8;

Fig. 10 is a part sectional and elevatlonal vi w in the direction of the arrows ill-id shown in Fig. 11 is a sectional view on the line ll-il of Fig. 10 showing the upper rollers in place and operatively engaging the weldrod, this arrangement being the one used for welding circumferential seams;

Fig. 12 is a sectional view on the line 52-42 of Fig. 10 and showing the lower rollers in place and operatively engaging the weldrod, this arrangement being the one used for welding longitudinal seams;

Fig. 13 is a sectional view on line l3--I3 of Fig. 11; i

Fig. 14 is a fragmentary enlarged side elevation of the weldrod feeding head with the weldrod shown in full and as being engaged by the lower set of rollers and including the contact shoes for conducting the welding current to the rodQthis arrangement being the one used for welding longitudinal seams; and

Fig. 15 is a view similar to Fig. 14 showing the alternative arrangement of the upper rollers engaging the rod for welding circumferential seams, and the electrical contact shoes turned at right angles to the position shown in Fig. 14.

In detail:

With reference to Fig. 1, an upright frame, suitably constructed, preferably from structural steel members, has guided therein, for iongitudinal movement only, a horizontal beam N moving on the roller bearing members I and 2 carried by the frame M.

The horizontal beam N carries a longitudinally disposed rack 3 engaged by a pinion drive 4 driven through suitable reduction gearing 5 from the electric motor 6 mounted on base I stationary with the frame M.

For carrying electric current to the weldrod feeding head to be hereinafter described, brackets 8 on frame M support shaft 9 and the latter carries reel H] on which is coiled the multiconductor cable H passing over the guiding idler roll 12 journaled on shaft l3 supported in brackets 14 also mounted on frame M: the conductor cable I i is led along the beam N to the vertical guideway i5 at the end thereof and in which is the independent vertically adjustable column l6 held in position by locking screws H.

The work to be operated upon is indicated at O as a cylindrical member in Fig. 1, and rests upon longitudinally spaced pairs of rollers I8 and IE! (only one of each pair being shown) suitably journaled as indicated at 20 and 2!, respectively, upon stanchions 23 and 24 which are adjustable along a bed member 25; a motor 26, through appropriate reduction gearing 21 may drive one or more rollers of the pairs of rollers I8 or IQ for the purpose of moving the work past the weldrod when a circumferential weld is being accomplished, the movement of beam N taking care of longitudinal welds.

Centrally of the transverse dimension of the bed 25 is an upright 25 carrying a shaft 28 on which is journaled an idler 28. A cable 29 passes over the idler 28 and one end 30 f the cable is connected to a longitudinally sliding backingup member 3| having an adjusting jack 32 engaging a weld seam backing-up strip 33 toassist in supporting the same against the weld seam boundaries; the other end ofthe cable 29 is passed under one of a group of idlers 34 journaled on shaft 35 and mounted in frame M, thence over one of a group of idlers 36 journaled on shaft 31 mounted in frame M and attached, as at 38, to the forward portion of beam N; similarly, one end of cable 39 is attached, as at 40, to the opposite side of backing-up member 3| from the attachment of cable 29 and passes under its idler section 34, thence over its particular idler section 36 and is secured to the after end of beam N.

With the arrangement described in the foregoing paragraph it will be observed that movement of beam N effects a corresponding movement of backing-up member 3|, and thus the weldrod and backing-up member are always automatically maintained in proper relative position for cooperation, either for a longitudinal, circumferential or transverse seam.

The weldrod feeding head is generally indicated in Fig. 1 by the letter P and is mounted at the lower end of the upright column is carried by the front end of beam N to which it is secured by suitable studs or bolts 4| passing through the column l6 andentering the bracket 42 which has secured thereto a sector piece 43 held against displacement by bolts or studs 44 and key 45.

I refer now to Figs. 3, 4, 5, 6, 7, 8, 9, 10, 12 and 14 which show the'details of my improved form of adjustable head, and the adjustment used for welding longitudinal seams.

A journal pin 46 is integral with or secured to the bracket 42 and extends outwardly therefrom at right angles, and is provided with a threaded member, such as either a stud or nut 41, at its outer end for purposes of retaining the elements hereinafter described in their assembled relation with respect to journal pin 46 and bracket 42.

Mounted upon journal pin 46 is the movable frame 48, the lower portion of which is provided with bearings 49 and 50 (see Fig. 7), with bushings as shown, and between which is received the worm gear meshing with the teeth of sector 43; the worm gear 5| is secured by a key 52 to the shaft 53 turning in the bushings of bearings 49 and 50, the shaft 53 being held at one end against longitudinal displacement by the nut 54 and washer 56 on the threaded extension 55, while the other end has keyed thereto, as at 51, the bevel gear 58 secured in place by the nut 59 on the threaded extension 50 of said shaft 53.

The frame 48 of the weldrod feeding head also has integral therewith a bracket bearing GI which journals shaft 62 secured against longitudinal movement by the bevel gear 83 fixed thereto and engaging bevel gear 58 and by collar 64; on the end of shaft 62 opposite bevel gear 63 is a handwheel 65 held by a key (not shown) and nut 66.

It will be obvious from the foregoing description relative to the mounting of the weldrod feeding head frame 48 on the journal pin 46 that movementof the handwheel 65 will displace the said frame 48 angularly by reason of the meshing bevel gears 58 and 63 which rotate shaft 53 and its worm 5|, which latter engages the fixed sector 43; the object of such angular displacement of the welding head frame is to vary the angularity of theweldrod in one vertical plane, as will appear as this description proceeds.

On the top of the weldrod feeding head frame 48 is a bracket 61 secured by bolts 68 and having bearings 69 and receiving the shaft 1| which, at one end, has keyed thereto a pinion 12 secured by nut I3 and engaging a rack 13* carried by frame 81, and at the other end bevel gear 14 is keyed and secured to the said shaft H (see Fig. 4) A bracket 75 held to the frame 48 by bolts I6 carries a bearing 11 journaling a shaft 18 having keyed and secured thereto a bevel gear 13 meshing with bevel gear 14 on shaft H, end play of shaft 18 being prevented by nut 80 and collar 8|;

said shaft 18 has a handwheel 83 secured thereto and held thereon by a nut 82.

In an upright plane at the side of frame 43 is the guide member 84 fixed with respect to the said frame 48 and having laterally extending parallel guide surfaces 85 and 36 upon which the movable mounted member 8! slides, the elements 88 and 89 being secured to member 81 and overlapping guide surfaces 85 and 86 as shown in Fig. 5 and held in place by bolts or studs 90.

It will thus be evident that with the mounting above described, and the pinion and rack arrangement as set forth, motion of the handwheel 83 will move the weldrod feed and adjusting mechanism lineally.

Thusfar there are three movements described. firstly, the movement of the entire welding head P through travel of the beam N, secondly, the angling movement of the weldrod feed and adjusting mechanism in the plane of movement of the entire welding head, this being accomplished by the handwheel 65; and thirdly, movement of the weldrod feed and adjusting mechanism lineally in a plane transverse to the movement accomplished by travel of beam N, but such movement by handwheel 83 is purely local for adjusting purposes .with respect to the welding groove.

The weldrod feed and adjusting mechanism has also another movement and that is angular movement in a plane of movement coinciding with the plane of movement by handwheel 83.

The movably mounted member 01 is formed at its outer end 9| so that it provides a transverse journal bearing 92, as shown in Figs. 5, 6, 8 and 10 and which receives the pintle 93 of the gear hous ing 94 for the gears driving the weldrod feeding rollers arranged in pairs X and Y at right angles to each other, the pair X being shown in Figs. 3, 4, 5, 10, 12 and 14 and for the purpose of feeding the weldrod while welding a longitudinal seam, and the pair Y being shown in Figs. 1, 11, and 15 and being for the purpose of feeding the weldrod while welding a circumferential seam.

The cap of the journal bearing 92 is recessed, as is also the outer end 9I of member 81 to accommodate a roller or frictionless bearing 95 and the whole is held in assembled relation by bolts or studs 96, felt or other grease retaining rings 91 being located on each side of said bearing 95.

Extending through the bearing 95 is pintle 93 in the form of a sleeve threaded at one end into a gear casing 94 as shown at 99, said casing supporting and carrying the pair of weldrod feeding rollers X and Y above mentioned. The sleeve 93 is prevented from working out by the set screw IOI. At the end opposite the threaded portion 99 of the sleeve 93 is keyed, as at I02, the sector member I03 which also has keyed and bolted thereto as at I04 and I05, respectively, the rack I06. The rack I06 is engaged by a worm I0'I' confined between bearings I08 and I09 of the member 81 which mount spindle IIO of handwheel III and to which spindle worm IN is keyed, as at II2, so that motion of the handwheel III serves to tilt or angle gear case 94 and with it the electrode or weldrod.

Mounted at the side of member 81 is a reduction gear housing I I3 surmounted by a vertically positioned electric driving motor I I4 which is reversible and drives the horizontal shaft II5 through the medium of the reducing gear in housing I I3 and which may be of any usual commercial type of the proper ratio and affording a rightangle drive.

The outer end of shaft -II5 passes through bearing support II6 carrying the ball bearing III and has keyed thereto the bevel pinion I I8,mesh ing'with a similar bevel pinion I20 keyed to stub shaft H9 and held thereon by a nut, said stub shaft II9 passing through ball bearings I2I in the sleeve 93 and the end opposite bevel pinion IIB carries a spur gear I22 keyed thereto and which by a system of spur gears to be hereinafter described, serves to drive the pairs of electrode or weldrod feeding rollers X and Y.

As stated, in case it is desired to weld a longitudinal seam the pair of rollers X is used. The

pair of feed rollers X are mounted on stub shafts I23 and I24 which, respectively, carry feed rollers I25 and I26 of the pair X keyed thereto as shown, the rollers each having a-resilient weldrod en'- gaging face such, for instance, as rubber. Shafts I23 and I24 are mounted in ball bearings I21, I20 and I29, I30, as shown, and spur gears I3I and I3I are keyed to the shafts I23 and I24 and intermesh. The spur gear I3I has a double width face and meshes with spur gear I22 so that as shaft H5 is rotated by electric motor II4 the pair of weldrod feeding rollers X rotate to positively feed the electrode orweldrod gripped therebetween and indicated by the letter Z.

Also spur gear I22 engages idler spur gear I32 mounted on stub I33 and which, in turn, meshes with spur gear I34 keyed, as shown, to shaft I35; shaft I35 is mounted on ball bearings I36 and I3! and carries bevel gear pinion I38 meshing with bevel gear pinion I39 keyed to shaft I40 of a pair of shafts, the other of which is I and which are mounted in ball-bearings I42, I43 and I44, I45, as shown.

The shafts I40 and MI have keyed thereto meshing spur gears I46 and I41, respectively, and at theirouter ends may be mounted the rollers I48 and I49 constituting the pair of weldrod feed rollers Y, each resiliently or yieldingly faced. in the same manner as the pair X, but with their axes at right angles to the axes of the rollers constituting the pair X.

The rollers I25 and I26 constituting the pair X and the rollers I48 and I49 constituting the pair Y are each removably secured by suitable nuts or the like to their respective shafts so that when longitudinal seams are .being made the rollers I48 and I49 may be readily removed and when circumferential seams are being made the rollers I25 and I26 may be readily removed.

The weldrod Z shown in Figs. 14 and 15 is of the coveredtype and has formed thereon spaced bumps 300 which extend through the covering and are adapted to be engaged by contact shoes in the casing 301 for conducting welding current to the rod. It will be observed that I have shown in Fig. 14 the bumps 300 as being at right angles to a plane normal to theaters of the rollers Y, the reason being to prevent engagement under pressure of the hard metal bumps with the rubber forming the surface of the rollers, which engagement might cause undue wear of the latter.

The casing 30I is suspended from the head by means of a swivel joint 302 so that the casing maybe turned about the axis of the weldrod to provide for the just described desirable arrangement of the weldrod and roller in welding both longitudinal and circumferential seams. The nut 303 serves to secure the casing 30I in either position. v

From the foregoing it will be apparent that regardless of the angular position of the weldrod due to the movement of handwheels 65 or III, or the change in horizontal position of the weldrod feeding head due to movement of the handwheel 83, the feeding mechanism of the weldrod will not be thrown out of action.

The welding machine previously described is used in connection with the circuit and controls indicated in Fig. 2 wherein the work is indicated at I50 and the weldrod at I5I, the bumps or bare contact faces 300 of which are engaged by the diagrammatically represented current carrying shoes I54. The weldrod I5I is, as previously de- A jet of inert or reducing gas may be fed through the nozzle I55 from the supply pipe I50, controlled by either or both the solenoid operated valve I51 and the manually operable valve I56 to the vicinity of the arc between the weldrod I5I and the work I50.

The are circuit includes a power supply which is preferably alternating current at a suitable voltage, for example 220 volts, which supply is connected to the'primary of a welding transformer I59 and adjustable reactor I60 described in a separate application. One side of the secondary of the transformer and reactor is connected by a lead I6I to one pole I62 of a magnetically operated switch D, the other pole I64 of which is connected to the current carrying shoes I54 engaging the weldrod I 5I The other side of the transformer is connected by a lead I65 to the work I50; thus when the switch D is closed an arc may be struck and held between the end of the weldrod I5I and the work I50.

After the arc is started, it may be controlled by regulating the rate of feed of the weldrod I5I through control of. the speed of the reversible weldrod feed motor H4.

In order to effect control of the reversible weldrod feed motor I I4, in the form of the invention which is illustrated, a direct current supply ,,line. at a suitable voltage, for example 60 volts, is provided. As shown, the direct current supply line includes leads I66 and I61; and, as will presently appear, through the medium of con trol apparatus energized by this supply line and control apparatus actuated by the changing characteristics or the arc, there is obtained an automatic regulation of the are.

With the circuit shown, the operator adjusts the weldrod I5I to the work I50 and closes the "start-stop" switch, thereby establishing connection between the contacts I60 and I69 thereof, and as a result current will flow from the lead I61, through the contacts I68 and I69, the solenoid which operates the switch A, thence back to the other side I66 of the supply line. Switch A will then close and current will flow therethrough from the side I61 oi the supply line, through the solenoid which operates the switch 0, and thence back to the other side I66 of the supply line. When switch C closes, current will flow from the lead I61 through the contacts of the switch C and through the solenoid which operates the switch D and then back to the lead I66. When switch D closes, thearc circuit from the transformer I59 will flow through the contacts I62 and I6 and permit the initiation of an are between the weldrod I5I and the work I50 by means of momentarily placing acrrms the gap a carbon pencil or the like.

The closing of the switch D also permits current to flow through the solenoid which operates an arc control relay switch F, having a core or plunger I63 which operates two sets of contacts I10, "I and I12, I13 respectively. When the solenoid of switch F is energized, the core I63 thereof will be moved upward to establish first connection between contacts I10, HI and after this connection is made, further movement of the core will break the connection between contacts I12, I13. The core of the switch F is urged downward by a suitable spring I14 or the like. The closing of the contact I10, I1I of the arc control relay switch F, causes current to flow from the conductor I61 through the solenoid for operating the switch B and back to the conductor I66, thereb operating the switch to close contacts 200, I

solenoid is designed to overcome the force or the spring 201 when the voltage flowing therethrough exceeds a predetermined amount, for example 50 volts. A resistor I16 of predetermined characteristics, for example, 20 ohms is arranged in shunt-relation with contacts 208 and 26! oi switch E, and both are in series with the circuit which includes the solenoid of switch F, the purpose ol. such arrangement being to provide for the protection of the solenoid of switch F before thearc is struck or in case the voltage becomes excessively high due to a long are or failure 01' the are. With the striking of the arc, the voltage will drop and spring 201 will close switch E,

thereby shunting the resistor I16.

With the foregoing arrangement, should the arc lengthen, thereby causing an increase in voltage through the solenoid of the arc control relay switch F such solenoid will move the relay plunger I63 upward to a point where contacts I12 and I13 are broken, but not sufllcient to break contacts I10, "I and as a result current will flow through a shunt circuit including a manually adjustable rheostat I11 arrangedln series with the field of the motor II 4. This action will cause the weldrod feed motor to increase its speed, and thereby move the end of the weldrod I5I. nearer the work I50 at an increased rate over the normal rate of consumption, thus shortening the arc length and reducing the voltage through the solenoid of switch F, which causes the relay plunger I63 to be moved downward by the spring I" suiiicient to re-establish connections between contacts I12 and I13, and shunt out the rheostat I11, but Insumcient to break the connection between contacts I10 and "I. The weldrod motor will then operate at its former speed to feed the weldrod toward the work. The speed at which the motor I I4 operates when the connection between contacts I12 and I13 is broken, depends upon the previously selected adjustment of the rheostat I11. Also, an arc length control rheostat I18 which is in series with the solenoid of switch F, is adjustable to absorb more or less of the arc voltage so as to alter the critical arc voltage at which solenoid of switch F breaks the connection between contacts I12 and I13. Therefore, the rheostat I18 functions to determine the arc length at which stable operation.

is maintained.

Should the weldrod freeze to the work I50, the resistance to fiow set up by the gap, of course, drops-to zero, thereby short circuiting the solenoid of the arc control relay switch F. As a result spring I14 will opencontacts I10, "I and thereby de-energize the solenoid of switch B. A spring 210 will break the connection between contacts 200, 20I and 202, 203, and establish connection betweencontacts 20I, 204 and 203, 205, thereby causing the current to flow through the armature of the motor Ill in the reverse direction and cause the motor to operate to move the weldrod away from the work to re-establish the arc. As the contacts I12, I13 are in engagement, the motor will operate in the reverse direction at the slow speed, thereby facilitating the reestablishing of the arc. When the arc is re-established, current will then flow through the solenoid of switch F and cause contacts I10 and HI to be re-engaged, and thereby energize-the solenoid of switch B, and cause the latter to again close contacts 200, ZOI and contacts 202, 203, and cause the current to flow through the motor in a directio tacts I12, I13 of the switch F open and close according to slight adjustment of the relay plunger responding to variations in the voltage due to variations of arc length. It will thus be evident that the contacts I12, I13 of the arc control relay switch F place the weldrod field rheostat I11 in and out of the circuit of the field of the motor H4, and with this arrangement the weldrod feed motor is caused to operate at a predetermined fast rate, or a .predetermined slow rate according to whether thecontacts I12, I13 are open or closed.

The predetermined fast rate of the weldrod feeding motor II4 must be such that the weldrod or electrode is fed to the work at a rate faster than it is consumed by the arc as otherwise the operation of the arc would be unstable; but the predetermined slow rate is preferably slower than the rate of consumption of the weldrod by the are, as otherwise the arc will continue to shorten, thereby causing the plunger of the are control relay switch F to drop, opening the contacts I12, I13, and de-energizing the coil of switch B which would cause the weldrod feeding motor III to reverse.

While I have shown one preferred embodiment of my invention it will be obvious to'those skilled in the art that it is not so limited, but is" susceptible of various changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed-thereupon as are imposed by the prior art or as are specifically set forth in the append-' 1 ed claims.

I claim 1. In an arc welding system, a movable work piece and a consumable weldrod included in an arc circuit, electrically energized means for normally imparting continuously uni-directional feeding movement to the weldrod forwardly toward the work, independently of the movement of the work, either at a rate faster or slower than a predetermined rate of weldrod consumption,

, and means responsive to arc voltage for normally continuously energizing the weldrod moving means selectively for faster or slower feeding accordingly as the arc length increases and decreases.

2. In an arc welding system, a relatively movable work piece and a consumableweldrod included in an arc circuit, a two-speed electrically driven weldrod feeding means arranged to continuously move the weldrod toward the work at a fixed predetermined uniform rate, one greater and the other less than the actual rate of weldrod consumption, means included in the arc circuit responsive to the energy of the arm for selecting the greater rate on lengthening ofthe arc and the lesser rate on shortening of the arc length from a predetermined arc distance, and means responsive to are energy for reversing the direction of weldrod travel only upon contact of weldrod and work piece.

- JAMES E. TRAINER. 

